(1) Field of the Invention
The present invention relates to a mechanism and method of mounting and dismounting an intermediate transfer unit, in particular relating to a mechanism and method of mounting and dismounting an intermediate transfer unit for use in an image forming apparatus, which includes an intermediate transfer unit as a separate unit from the apparatus body that is integrally constructed of an intermediate transfer element to which a toner image formed on a photoreceptor drum is temporarily transferred and a drive portion for driving the intermediate transfer element, and in which the intermediate transfer unit is constructed so that it can be mounted to and dismounted from the apparatus body.
(2) Description of the Prior Art
Conventionally, in the field of image forming apparatuses such as printers, facsimile machines and the like, there have been known image forming apparatuses which adopt a so-called intermediate transfer system in which the toner formed on the photoreceptor drum is temporarily transferred (in the primary transfer) to an intermediate transfer element (e.g., transfer belt) and the toner image is then transferred from the intermediate transfer element to a recording medium (in the secondary transfer). As such image forming apparatus using this system, there has been known a configuration in which a transfer belt as the intermediate transfer element and a driver or the like that drives the belt are integrated into a unit so as to improve assembly and maintenance performance.
However, in this configuration, if a paper feed jam or the like occurs inside the intermediate transfer unit, the toner image remnant of the final image may remain on the transfer belt, so that it is not preferable from a security viewpoint if the intermediate transfer unit is simply drawn out.
In particular, in a case of a configuration where the belt conveyor path in the intermediate transfer unit is arranged with a transfer cleaner for cleaning the transfer belt disposed at its one end and the transfer station for the secondary transfer disposed at the other end or on the opposite side, the toner image remnant after the secondary transfer is left on the transfer belt in the section from the secondary transfer station to the transfer cleaner, making the problem outstanding.
Further, if the intermediate transfer unit with toner image remnant and other remaining toner residing on the transfer belt is drawn out to perform maintenance of the apparatus body and intermediate transfer unit, there is the problem that the remaining toner is prone to make dirty.
As a countermeasure against dirty due to remaining toner in the prior art, there is a proposal of a color image forming apparatus configuration using an intermediate transfer belt system with which cleaning performance is improved by creating a toner dam by supplying supplemental toner for cleaning to the press-contact area of the cleaning blade so as to prevent the toner from slipping through the cleaning blade (see patent document 1: Japanese Patent Application Laid-open 2006-84842).
In the above conventional technique, it is possible to improve cleaning performance for the image support by applying supplemental toner for cleaning to the image support, however, among the above conventional problems the technique does not bring any solution to the security problem of the toner image remnant being left on the transfer belt when the intermediate transfer unit is drawn out.